Penetrator



WlLLEY Feb. 12, 1935.

wanted Feb. 12, 1935 f i 1,9'91,Z3'8

UNITED STATES PATENT OFFICE -rmvn'rmi'ronA rzy n. wiuey, Demitmcn. 'Application June 15, 1982, serial No. 617,405' '1 cisims. (ci. zes-18) This invention relates to penetrators for testthe invention are hereinafter more fully deing penetration hardness of metal such as steel scribed andclaimed and the preferred form of or the like. The penetrator hereinafter deconstruction by which these objects are attained scribed is adapted for use in any of the well 'is shown in the accompanying drawing in known types of machines for testing the hardwhichi ness of the metal by penetration. In 'using a Fig. 1 is a sectional elevational view of my imtesting machine wherein a major and a minor proved penetrator.

load is applied to the penetrator it is usually Fig. 2 '-is an end view thereof.' customary to place the end of the penetrator 4 Referringto' the drawing, the holder` 1 is caragainst the surface to be tested and then apply ried in a testing machine (not shown) and is 10 a minor load to the penetrator 'then measure the formed with a recess 2 in which the penetrator depth of penetration of the indentation and then 3 is positioned the same being held in place inv apply a heavier load to the penetrator, the difthe recess by pouring 'the molten metal 4 in the ference in depth of the two indentations caused recess and allowing the same to harden whereby by application of a minor and major load being the penetrator 3 is held in its correct position 15 interpolated whereby the penetration hardness when the metal 4 has hardened.` This, of course, of the material may be determined. This peneforms no part of the invention as any desired trator is equally as well adapted for use in mameans may be used for holding the penetrator chines not using the majorand minor load method in the holder. The penetrator 3 is preferably a of determining hardness. The common type of diamond and is formed with the pyramidal 20 penetrator in ordinary use is formed with a shaped end 5 formed by the fiattened sides 6 the spherical segmental tip and frustroconical sides. included angle between two opposite sides beingl This type of penetrator is more or less inaccurate approximately 121 degrees. The tip of the peneas it is practically impossible to form a penetrator 3 is formed with the fiattened end '7 which trator in which the spherical segmental end has prevents any tendency of the holder 1 to drift 25 the correct curvature and the sides the correct from its longitudinal axis in-the event the'pene-f angle and further in testing the material the trator encounters a hard or soft spot in the rounded point of the penetrator has a tendency metal during the testing operation. It will be to drift out of Vertical alignment with the lonfurther noted that the meeting edges 'of the flat gitudinal axis when a hard or soft spot is enside 6 will act as cutters during the impression 30 countered during the ltime of penetration thereoperation and will permit the penetrator to by giving an improper reading. more easily enter the surface of the metal being It has further been found that in using apenetested thereby prolonging the life of the penetrator of this character that the life thereof was trator.

extremely short and due to the ltime and laborA From the use of this penetrator in service the 35 involved in producing these penetrators the cost conclusion is reached that its ease in penetraof operation of the testing machine was 'extion and the tendency of the penetrator to tremely high.v w udrift under load is materially decreased due It is therefore an object of this invention to to the fact that, in forming the penetrator with 40 provide a penetrator which will give an extremethe series of flat faces in pyramidal form, the 40 ly accurate hardness test due to the fact that it ridges between the faces whichv also extend from is possible to form the sides of the penetrator to the point upwardly at an angle one to the `other the exact required angle and further that since act as cutters as previously stated and as the the end of the penetrator is fiattened that there penetration proceeds continuously extend outispractically no tendency of the penetrator to wardly into the metal. Thus the metal dis- 45 drift when the major and minor loads are applaced or extruded by each face is segregated plied thereto. v v i from that extruded by the contiguous faces Another object of the invention resides in the whereby the pressures about'the tool are equalprovision of a. penetrator .of pyramidal shape ized. With the ucone" type of penetrator prehaving a fiattened end portion the -meeting edges viously in use, one side of the cone in penetrat- 50 of the sides of the penetrator acting as a cutter ing metal of somewhat greater hardness, than whereby the penetrator may be more easily inthe opposite side of the cone tends to drift and serted in the metal thereby prolonging thelllfe thus gives an inaccurate depth reading as part of the penetrator. v. of the force of the load is diverted to side presl These objects and the several novel featuresof sure. By separating the surface beingentered by means of the ridges between flat surfaces which ridges extend at an equal angle one to'v another the metal will more easily extrude due to each separate space between the ridges being separated from that extruded by the adjacent faces. f i

Therefore each flat surface more readily extrudes the metal and does not tend to compact; the same`as is more nearly the case with the cone type penetrator. This ease of penetration and lessened tendency to compact the ma.- terial as produced by my construction is of importance for the following reasons:

These penetrators are all tested as to penetration by a test block of known hardness and after repeated tests the surface of the block is removed to below the recesses formed therein by previous. trials and with a cone penetrator the resurfaced metal is found to contain many hard spots and therefore does not provide a test block of uniform hardness as was its original condition. This I conceive' to be due to the fact that the metal is compacted by the series of tests made thereon. With my improved penetrator the resurfaced block does not appear to in any material degree at least have lost its uniformity in respect to hardness. This I attribute to the fact as above stated, Athat the metal more readily extrudes and that probably the only real compression of metal forward of the point is only that produced by the metal engaged by the extreme preferably flat point penetrator which should in most cases be not greater than four one-hundredths of a millimeter across opposite sides.

It has been found that it is possible to make a penetrator of this character which is more accurate and which is cheaper to manufacture than the commonly known cone end penetrator. This is due to the fact that it is possible to use an index machine for facing the sides so that absolute precision may be obtained in making a penetrator of this character while in making a penetrator of the cone type it is necessary to rotate the penetrator at an extremely high rate of speed during the forming operation and very often an extremely slight wear in the rotating parts of the machine will form an imperfect penetrator which will not give an accurate reading when used in a testing machine.

From the foregoing description it becomes evident that I have provided a penetrator which will have an extremely long life and in which there is no tendency for the same to drift during the testing operation when the penetrator encounters a hard or soft spot in the metal, further that the device is cheaper and more accurate to manufacture than the ordinary cone type of penetrator.

Having thus fully described my invention, its utility and mode of operttion, what I claim and desire to secure by Letters Patent of the United States is- 1. A device of the character described comprising a truncated pyramidal end portion, the tip thereof being a plane surface' at a right angle to the longitudinal axis of the pyramidal end portion, the peripheral edge of the plane surface providing a cutting edge.

2. A device of the character described comprising a truncated pyramidal end portion, the included angle between two oppositely disposed sides thereof being substantially 121 degrees and the tip thereof being a plane surface at a right angle to the longitudinal axis of the .pyramidal end portion, the peripheral edge of the plane surface providing a cutting edge.

3. A device of the character described comprising a truncated tapered end portion, the said end portion having more than three flat faces, the tip thereof being a plane surface at a right angle to the longitudinal axis of the pyramidal end portion, the peripheral edge'of the plane surface providing a cutting edge.

4. A device of the character described comprising a truncated pyramidal end portion having more than three flat faces, the included angle between two oppositely' disposed faces thereof being substantially 121 degrees, the tip of the pyramidal end portion being a plane surface at a right angle to the longitudinal axis of the pyramidal end portion, the peripheral edge of the plane surface providing a cutting edge.

5. In a device of the character described having a body and a pyramidal portion providing more than three practically flat faces, the ridges between the flat surfacesi terminating short of the extreme tip providing a point of a uniform uninterrupted flat surface occupying a plane at a right angle to the longitudinal axis of the pyramidal portion and of approximately four one-hundredths of a millimeter, a peripheral edge of which is a cutting edge.

6. A penetrator for testing the hardness of material through penetration thereof under measured load comprising a body having a truncated pyramidal end portion having a multiplicity of practically flat faces, the included angle between two oppositely disposed faces being in the neighborhood of 121 degrees and having a flat penetrating tip occupying a plane at a right angle to the longitudinal axis of the said' pyramidal end portion, the peripheral edge of the plane surface providing a cutting edge.

7. A penetrator comprising a metal body of the desired form, a tip of extreme hardness mounted in the body and having a plurality of fiat side faces forming a pyramid, the hard tip terminating in a plane surface at a right angle to its longitudinal axis, the peripheral edge of said plane surface forming a cutting edge.

FAY H. WILLEY; 

